First insights into soil fauna mapping across Europe using data from multiple databases

Soil fauna is one of the most important components of soil ecosystems. It is highly diverse and abundant, supporting essential ecosystem services. However, its use in management decisions has been limited by now. This is partly a result of missing data and knowledge for large-scale mapping and application. In this study, our objective was to shed light on these aspects by mapping the spatial distribution of representative groups of macro- and mesofauna. Specifically, we used publicly available data for Earthworms, Millipedes, and Springtails and mapped their abundance, richness, and diversity across Europe. We applied machine learning techniques to understand the spatial configuration of these soil fauna taxa as influenced by topography, climate, vegetation, land use, and soil properties. Our results showed that for Springtails, Earthworms and Millipedes, climate, vegetation, and land use were among the strongest predictors of species richness and diversity patterns, while abundance was mainly influenced by vegetation and soil properties. Although mapping provides a visual presentation of soil ecosystems and conservation trends, as well as soil biodiversity hotspots, we also found that soil mapping has a high degree of uncertainty, largely underestimated due to the highly endemic and patchy nature of soil fauna, with significant disparities in current data, including historical differences in methodologies and sampling efforts. Our study highlights the need to continue soil biodiversity monitoring efforts, promote data sharing, and conduct further research on soil biodiversity conservation and management.